Invalid default value for property error in class properties

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Greeting
I made a class and run dthe code in .m file
classdef myclass
properties (Constant)
a=physconst('LightSpeed');
b=a/2
end
end
it occurs error and says
Invalid default value for property 'b' in 'myclass':
Unrecognized function or variable 'a'.
physconst("LightSpeed") is a function in addon which name is 'Phased Array System Toolbox'
and its version is 4.3
a=physconst('LightSpeed')
b=a/2
I put thosdde two lines in command window
and it works fine...
so I have removed constant and tried to initialize them with class constructor
classdef myclass
properties
a;
b;
end
methods
function obj=myclass(obj)
a=physconst('LightSpeed');
b=a/2;
end
end
end
but the same error occured
I want to initialize my class property value with addon function but it have bring out error
How to deal with this error?

Accepted Answer

per isakson
per isakson on 24 Apr 2020
Edited: per isakson on 24 Apr 2020
In the properties block one must refer to a as MyClass.a when Constant.
>> mc = MyClass
mc =
MyClass with properties:
a: 299792458
b: 149896229
>> which physconst -all
C:\Program Files\MATLAB\R2018b\toolbox\shared\siglib\physconst.m
>>
where
classdef MyClass
properties (Constant)
a = physconst('LightSpeed');
b = MyClass.a/2;
end
end
In your second class definition the constructor
function obj=myclass(obj)
a=physconst('LightSpeed');
b=a/2;
end
shall be
function obj=myclass()
obj.a = physconst('LightSpeed');
obj.b = obj.a /2;
end

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